Television system



Feb. 19 1935. T, H, NAKKEN 1,991,409

TELEvIs/ION SYSTEM Filed Nov. .12, 195o 2 sheets-Sheet 1 FIG. 3

INVENTQR THEODURUS H N/:IKKE/V ATTORN EY Feb. 19, 1935. v T, H, NAKKEN 1,991,409

TELEVI S ION SYSTEM Filed Nov. 12, 19:50 2 sheets-sheet 2 INVENTOR Tf/EoDaRl/s H. NA KAE/v i BY ATTORNEY Patented Feb. 19, 1935 UNITED STATES TELEVISION SYSTEM Theodorus H. Nakken, Bronx, N. Y., assigner to Nakkcn Patent Corporation, New York, N. Y., a corporation of Delaware Application November 12, 1930, Serial No. 495,106

12 Claims. v (Cl. 178'69.5)

This invention relates to improvements in apparatus for television, picture transmission, and similar devices, and particularly to new methods for operating such systems.

In the transmission of pictures, diiculty has been experienced in securing and maintaining proper synchronization of the scanningdiscs and in securing and maintaining proper framing of the transmitted image. 7

An object of this invention 1s to improve the accuracy of synchronization of the scanning discs in a picture transmitting system. i

Another object is to secure automatic framing of the reproduced picture in a picture-transmitting apparatus.

Still another object is to adjust automatically the phase position of the scanning disc in a picture transmitting system.

Still another object is to generate in a picture quency adapted to insure both synchronization and isochronism for framing.

A still further object is to synchronize the scanning discs in a picture transmitting system both in respect to the scanned lines, and with respect to the entire picture, by a single system, which is further adapted to be automatic in its action.

Another object is to transmit a picture and maintain synchronism of rotation of the scanning discs, and simultaneously to obtain phase coincidence of the scanned lines, and phase coincidence or isochronism of the respective scanning discs.

In the prior art of picture transmission, it has been common to utilize rotating discs having a series of spiral scanning holes therein, at both receiving and transmitting stations, and to rotate the discs in synchronism, a light sensitive cellY .40 being associated with the sending disc and a rapidly variable light system with the receiving disc. In the operation of such a system, however, it is essential that the discs rotate in synchronism, that is, at the same speed, in order to bring the successive scanned lines int-o proper relationship. It is also necessary to secure phase coincidence between the sending and receiving discs in order ,to frame the received picture. Thus in order to receive a picture the speed of the receiving disc must be adjusted accurately to match that of the transmitting disc and, thereafter, the speed .must be temporarily changed slightly until the picture has been adjusted upward or downward on the receiving eld to bring it into frame, or

55 in register with the picture opening. This has transmitting system a cyclically varying fre- -1 been found to be a delicate and diiiicult operation, which can be done only by the employment of considerable manual dexterity.

The invention here disclosed provides a simple, automatic means for securing and maintaining synchronism of the receiving disc with the sending disc, and for automatically adjusting the phase relationships of the respective discs to coincidence so that the received picture is framed without manual intervention. 'I'his is accom- 1 plished by providing in the transmitting circuit a series of synchronizing impulses generated by the transmitting disc as shown in my copending application, Serial No. 488,709, iiled October 15, 1930, cyclically varying the frequency of the'syn- 1 chronizing impulses, and adjusting a cyclically varying series of members at the receiver into phase coincidence with the cyclically varying impulses.

The above objects are thus accomplished by 2 providing in the television system a plurality of cyclically varying synchronizing impulses, by producing them from a contrasting curved line upon the transmitted picture, and by adjusting a series of cyclically varying members upon a re- 2 ceiving element into coincidence with the cyclically varying impulses.

Other objects and structural details of this invention will be apparent from the following description when read in connection with the ac- 3 companying drawings, whereinzf- Fig. 1 is a view of a picture prepared for transmission according to the process of this invention.

Fig. 2 is a. diagrammatic representation of cir- 3 cuits and apparatus of the device of this invention, and I Fig. 3 is a diagrammatic representation of the magnetic adjusting member.

Referring to Fig. 1 a picture 1, which may con- 4 veniently be a motion picture iilm as shown, or may be any other suitable picture, 'is prepared with a curved margin line 2 of high contrast as shown. If the picture is of light tone, the line 2 may be black. If the picture is of dark tone the 4 line 2 may desirably be white or light. Alternatively if the picture is of extremely hign contrast such as a black line drawing, theline 2 may consist of alternate black and white portions as shown in my copending application previously nl mentioned. It should desirably have a substantial width, in order to provide a substantial impulse in the photo-cell system.

The picture is shown as prepared for transmission by the application thereto of a curved margin upon one side. The margin may be applied to both sides if desired, and may take various forms, both margins being curved as indicated in the drawing, or one may be curved and the other straight. Alternatively an angular margin may be provided which may take the form of a V-shaped line, with the vertex at the center, or may take anyone of various other forms which will be obvious.

The picture of Fig. 1 may be transmitted by the system of Fig. 2, in which a scanning disc 3 having a series of spiral holes 4, and magnetic material projections 5, is rotated between the picture and a photo-electric-cell 10. The fluctuating output of the cell 10 may be fed to an amplifier system 8 by way of wires 9 and transmitted therefrom to a receiving station. The spacing between the openings 4 is adjusted according to the width of the picture at the point at which the individual scanning hole 4 crosses the picture, thus permitting each scanning hole A to be followed by the next as soon as it has completed its traverse to and over the curved line 2 on Athe picture. The spacing of the scanning holes 4 thus is a maximum at the middle of the spiral and less at each end of the spiral by an amount corresponding to the reduction inlengths of lines across the picture, produced by the curvature of the margin 2.

.In preparing therscanning disc 3, the number of holes 4 in the spiral will determine the number of scanning lines across the picture 1, and the total length of the spiral from start to finish will equal the sum of the lengths of the scanned lines across the picture. Accordingly, the distance from the rst scanning hole to the second scanning hole will be equal to the width of the picture at the top. 'Ihe distance from the second scanning hole to the third similarly will be equal to the distance across the picture at the level of the second scanningu line. If there are 48 openings, and 48 scanning lines, the second scanning line will be one forty-eighth of the height of the picture lower, and the length of the scanning line and similarly the spacing between the holes will be changed by the amount incident to the curvature of the margin of the picture. This change is small and cannot be shown accurately upon 4the drawing but is suillcient for the purpose. As indicated'by the difference in length of the scanning lines in Fig. 1 the difference in spacing of the scanning holes between the center of the spiral and the ends of 4 the spiral may amount to as much as twenty (20) percent, or even more.

In operation, each scanning hole produces a strong impulse in the photo-cell and its system when it passes the margin line 2, according to the system disclosed in the previously mentioned application. In addition the time between successive pulses varies according to the position ofthe scanning disc in its rotation cycle.

Alternatively, impulses may be obtained from an electro-magnetic system as vshown in Fig. 2-

in which the magnetic material projections 5 are spaced on corresponding radii with the scanning holes 4, thereby being separated by a maximum spacing at the middle of the scanning spiral and spaced with a lesser separation at the ends of the scanning spiral.- y. The magnetic material projections 5 cooperate with a magnetic system 6, as shown in greater detail in Fig. 3 to produce electric impulses therein, which are fed in parallel with the impulses from the photo-cell to the amplifier and transmitter 8. The impulses may conveniently be controlled by a resistance 11 and a condenser 12 cooperating with other appropriate impedance members.

For the receiving system a similar device according to the structure of Fig. 2 may be utilized, in which the element 10 is a neon tube or other light source adapted to rapid variation. In the receiver the member 8 is an appropriate receiving amplifier supplying energy from the sending system through the leads 9 to the light member 10. Simultaneously impulses areI supplied from the amplifier 8 to the magnetic system 8 by way of the coil 7, through the resistance 1l and condenser 12 which serves to limit current pulses, passing substantially only the relatively powerful impulses provided by the sending system either from the contrasting margin 24 of the picture or from the magnetic system operated by the projections on the scanningdisc.

In operation, the transmitted signals, made up of picture impulses according to the systems previously used and the powerful synchronizing impulses added according to this invention, are applied to the light cell 10 and the magnetic system 6. The presence of the synchronizingimpulses in the system 6 tend to speed up the receiving disc if it is not quite up to speed by exerting a magnetic pull upon the successive magnetic material projections 5 as they enter the fleld of the magnet 6; or to exert a magnetic drag upon the disc by retarding the projections if they tend to leave the field sooner than proper.

The magnitudes of these forces are however such that in order for a sulcient accelerating or retarding force to be applied, it is necessary that substantially all the projections 5 arrive under the magnetic member 6 at the proper time to be met by the controlling impulses. If the disc is out of phase with the controlling impulses, a few only of the projections will be subject to control, not enough to hold the disc in speed synchronism. Accordingly it will advance or retard according to its tendency until a greater number of the projections meet the controlling impulses at the proper iristant. The disc will thus be allowed to overspeed or underspeed by an appropriate amount until it reaches phase equality or isochronism with the transmitting disc, at which point all of the projections upon the disc reach the inuence of the magnetic system 6 at substantially the same relationship, to the incoming pulses. When this condition is reached suilicient accelerating or retardng force is applied to the disc to hold it in speed synchronism, and the picture receiving device is both synchronized and framed...

My invention thus provides a picture system in which the usual light intensity variations of the picture are transmitted, together with a series of powerful impulses synchronizing superposed upon them. 'Ihe superposed pulses provide a minimum frequency which is always present, and which improves the accuracy of transmission and obtains correct transmission of uniformly tinted surfaces, as described in my previously mentioned copending application. My invention not only provides the powerful impulses of a minimum frequency, but varies the minimum frequency cyclically at a period corresponding to the rotation of the scanning discs.

Control means upon the' receiving disc are spaced at similarly varying gintervals, so that when the sending and receiving discs are in synchronism and correct phase relationship, the powerful transmitted impulses co-incide with the holding it both in phase and in synchronism; or

otherwise stated, hold it in synchronism and at zero phase displacement. Furthermore, the invention provides a system in which the receiving disc may be given a tendency to run at a speed diierent from synchronous speed, under which condition the responsive means upon the receiving disc will permit a shift of its phase relationship to the incoming signals from the transmitting disc until it has reached a position of substantially zero phase displacement from the transmitting disc, whereupon it is locked into step, thereby ,framing the received picture.

But my invention I have thus provided a new and useful system for transmitting pictures in which both synchronism and zero phase displacement are automatically obtained and maintained, thereby insuring the production of an undistorted picture in good frame in the receiver opening.

While there is here described in detail but a single embodiment of the device of the invention, certain modifications are suggested, and other modifications are possible without departing from the spirit thereof. It is desired, therefore, that only such limitations shall be imposed upon the appended claims as are stated therein or are required by the prior art.

2. In combination in television transmitting and receiving apparatus, means bearing the picture to be transmitted having a curved contrasting margin; scanning means for converting the varying light intensities of said picture into electrical impulses andffor creating auxiliary electrical impulses unequally time spaced from said curved margin; means for transmitting all said electrical impulses; receiving apparatus including a rotatable receiver member for reproducing the picture impulses; and means responsive solely to said unequally time spaced electrical impulses produced by said curved margin for controlling the rotation of said rotatable receiver member.

3. The method of transmitting pictures which comprises producing and transmitting incomplete cycles of electrical impulses corresponding to varying light intensities of the picture to be transmitted and interspersed cyclically varying series of synchronizing impulses, operating a receiving scanning disc at a speed which tends to depart from synchronism, and holding said disc to synchronous speed by interaction between said synchronizing impulses and responsive members upon said disc.

4:. The method of picture transmission which comprises forming a eld of view of varying scanning length throughout, scanning said iield of view along lines of different lengths and transmitting a series of synchronizing impulses unequally time spaced in accordance with the lengths of said lines. e

5. The method of picture transmission which comprises'scanning separate small areas of a iield of view in successive groups of diierent sizes and transmitting a series of synchronizing impulses unequally time spaced in accordance with the size of said groups.

6. In a picture transmitting system, a scanning disc having a spiral of openings therein positioned at cyclically varying intervals, and a plurality of control members similarly positioned at cyclically varying intervals.

7. A television scanning disc comprising in combination a disc having a plurality of viewing openings therein, and a plurality of magnetically responsive members positioned at cyclically varying intervals.

8. In a television system, a scanning disc having a plurality of viewing openings, and a plurality of magnetic material members respectively positioned at cyclically varying intervals, and a magnetic system cooperating with said magnetic material members and adapted to receive cyclically varying synchronizing impulses.

9. In a television system, a scanning disc,

means for producing cyclically varying series of electrical impulses in synchronism with the rotation thereof, the duration of each said series being less than a complete cycle, means for transmitting said impulses, means for producing and transmitting a second cyclically varying series of synchronizing electrical impulses interspersed with said rst series, a reproducing scanning disc, means for driving said disc at a speed which tends to depart from synchronism, and means cooperating between said disc and said synchronizing impulses to maintain synchronism and phase coincidence of said disc with said transmitting means.

10.-'In a television system, a scanning disc having a plurality of viewing openings, and a pluralityof magnetic material members respectively positioned at cyclically varying intervals; and a magnetic system cooperating with said magnetic material members and adapted toreceiving cyclically varying synchronizing impulses, said magnetic system being adapted to exert a controlling force upon said magnetic members, varying according to their displacement from proper position.

11. In a picture transmission system, means other and interspersed 'between said seriesl of variable light intensity impulses.

l2. In a picture transmitting system, a synfor producing auxiliary irnchronizing element comprising a rotary member having around the periphery thereof a plurality of unequally spaced teeth of magnetic material. v

TIMODORUS H. .MLM N, 

